Add a blend animation

simgear/scene/model/animation.cxx

@@ -91,6 +91,31 @@ set_scale (sgMat4 &matrix, double x, double y, double z)
   matrix[2][2] = z;
 }
 
+/**
+ * Recursively process all kids to change the alpha values
+ */
+static void
+change_alpha( ssgBase *_branch, float _blend )
+{
+  unsigned int i;
+
+  for (i = 0; i < ((ssgBranch *)_branch)->getNumKids(); i++)
+    change_alpha( ((ssgBranch *)_branch)->getKid(i), _blend );
+
+  if ( strcmp("ssgLeaf", _branch->getTypeName()) &&
+       strcmp("ssgVtxTable", _branch->getTypeName()) &&
+       strcmp("ssgVTable", _branch->getTypeName()) )
+    return;
+
+  int num_colors = ((ssgLeaf *)_branch)->getNumColours();
+
+  for (i = 0; i < num_colors; i++)
+  {
+    float *color =  ((ssgLeaf *)_branch)->getColour(i);
+    color[3] = _blend;
+  }
+}
+
 /**
  * Modify property value by step and scroll settings in texture translations
  */
@@ -414,6 +439,53 @@ SGRotateAnimation::update()
   ((ssgTransform *)_branch)->setTransform(_matrix);
 }
 
+
+////////////////////////////////////////////////////////////////////////
+// Implementation of SGBlendAnimation
+////////////////////////////////////////////////////////////////////////
+
+SGBlendAnimation::SGBlendAnimation( SGPropertyNode *prop_root,
+                                        SGPropertyNode_ptr props )
+  : SGAnimation(props, new ssgTransform),
+    _prop((SGPropertyNode *)prop_root->getNode(props->getStringValue("property", "/null"), true)),
+    _offset(props->getDoubleValue("offset", 0.0)),
+    _factor(props->getDoubleValue("factor", 1.0)),
+    _table(read_interpolation_table(props)),
+    _has_min(props->hasValue("min")),
+    _min(props->getDoubleValue("min", 0.0)),
+    _has_max(props->hasValue("max")),
+    _max(props->getDoubleValue("max", 1.0)),
+    _prev_value(1.0)
+{
+}
+
+SGBlendAnimation::~SGBlendAnimation ()
+{
+    delete _table;
+}
+
+void
+SGBlendAnimation::update()
+{
+  double _blend;
+
+  if (_table == 0) {
+    _blend = 1.0 - (_prop->getDoubleValue() * _factor + _offset);
+
+    if (_has_min && (_blend < _min))
+      _blend = _min;
+    if (_has_max && (_blend > _max))
+      _blend = _max;
+  } else {
+    _blend = _table->interpolate(_prop->getDoubleValue());
+  }
+
+  if (_blend != _prev_value) {
+    _prev_value = _blend;
+    change_alpha( _branch, _blend );
+  }
+}
+
 
 
 ////////////////////////////////////////////////////////////////////////

simgear/scene/model/animation.hxx

@@ -221,6 +221,28 @@ private:
   sgVec3 _axis;
 };
 
+/**
+ * Animation to blend an object.
+ */
+class SGBlendAnimation : public SGAnimation
+{
+public:
+  SGBlendAnimation( SGPropertyNode *prop_root,
+                      SGPropertyNode_ptr props );
+  virtual ~SGBlendAnimation ();
+  virtual void update();
+private:
+  SGPropertyNode_ptr _prop;
+  SGInterpTable * _table;
+  double _prev_value;
+  double _offset;
+  double _factor;
+  bool _has_min;
+  double _min;
+  bool _has_max;
+  double _max;
+};
+
 /**
  * Animation to scale an object.
  */

simgear/scene/model/model.cxx

@@ -129,6 +129,8 @@ sgMakeAnimation( ssgBranch * model,
     animation = new SGTexTranslateAnimation(prop_root, node);
   } else if (!strcmp("texmultiple", type)) {
     animation = new SGTexMultipleAnimation(prop_root, node);
+  } else if (!strcmp("blend", type)) {
+    animation = new SGBlendAnimation(prop_root, node);
   } else {
     animation = new SGNullAnimation(node);
     SG_LOG(SG_INPUT, SG_WARN, "Unknown animation type " << type);